Nature of polarization fatigue in BiFeO3

TL;DR

This paper investigates how polarization fatigue in BiFeO3 varies with different switching paths, providing insights into the intrinsic fatigue mechanisms in low-symmetry multiferroic materials.

Contribution

It presents a detailed study of polarization fatigue in BiFeO3 for different switching paths and proposes a fatigue model to enhance understanding of fatigue in low-symmetry materials.

Findings

Polarization fatigue depends on the switching path in BiFeO3.

A fatigue model is proposed to explain the intrinsic fatigue behavior.

Understanding fatigue mechanisms can improve device reliability.

Abstract

As a room-temperature multiferroic, BiFeO3 has been intensively investigated for both magnetoelectric devices and non-volatile ferroelectric memory applications. Both magnetoelectric and ferroelectric memory devices have the same control knob: polarization switching by an applied electric field. Due to the rhombohedral symmetry of BiFeO3, there are four ferroelastic variances and three different polarization switching events: (1) 71{\deg} switching from r1- to r3+, (2) 109{\deg} switching from r1- to r2+ (or r4+), and (3) 180o switching from r1- to r1+ (the superscript + and - stand for up and down polarization, respectively). Each switching path is coupled to a different reorientation of the BiFeO3 unit cell, and hence different coupling to the magnetic order as well as different magnitudes of switchable polarization. A degradation of the ferroelectric properties of BiFeO3 will result in losing controllability of magnetic order switching in magnetoelectric devices and capacity for information storage in ferroelectric memory devices. Especially, polarization fatigue will directly restrict the reliability of the actual devices. Hence it is important to understand the intrinsic fatigue behavior of each polarization switching path in BiFeO3 thin films. In this communication, we report polarization fatigue in BiFeO3 depending on switching path, and propose a fatigue model which will broaden our understanding of the fatigue phenomenon in low-symmetry materials.